In acoustics, loudspeaker designers are always striving to produce loudspeakers with an acoustic radiation pattern with as much directional uniformity and as smooth a pressure response as possible.
WO 2006/092609 discloses how a dome-shaped diaphragm generating a spherical wavefront and a conical wave guide of limited angle can be arranged to produce a loudspeaker having conical dispersion characteristics with an exceptionally smooth pressure response.
There are occasions when it is desirable for a loudspeaker to produce a non axi-symmetric acoustic radiation pattern. For example, in an auditorium it may be desirable for the acoustic wavefronts to have different curvatures in the horizontal and vertical directions. In the prior art one technique for achieving this is to use horns which, by means of diffraction slots, forcibly shape the wavefronts to achieve the desired acoustic radiation pattern.